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AnsweredHot!How not to kill a dsPIC33EP?

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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/16 05:50:08 (permalink)
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You got me thinking.  I'm using a heat gun to pop the fried PICs off the board.  I thought maybe the 4-layer board might be delaminating and I could have lost a ground connection to one of the PIC pins.  I checked with an ohm meter and all 4 grounds are solid.

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crosland
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Re: How not to kill a dsPIC33EP? 2019/11/16 05:59:43 (permalink)
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When you supply power from the ICD/PICKit, you are disconnecting the USB power source, aren't you?
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/16 06:21:47 (permalink)
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I am not using USB power, no connection on the board.  Plus, I have never had a USB cable and ICSP connected at the same time.  This is a 1-off research project for proof of concept.  Basically I'm fuel injecting a single cylinder generator and controlling ignition timing with an automotive type ignition coil (plus a few other things).  The USB is for monitoring and tuning.  Thus no need for USB supplied power.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
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sborden
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Re: How not to kill a dsPIC33EP? 2019/11/21 05:26:01 (permalink)
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You might consider posting schematics at this point. If you can, of course.
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/21 09:43:28 (permalink)
5 (1)
When dsPIC #7 wouldn't even program a first time, I pulled it back off & started checking traces.  I found damage.  I don't know if it happened between #1 & #2 or #6 & #7, but I need to order a new board (4-layer = $300 US!).  I know there were errors with software & hardware when the 1st dsPIC went on.  I started correcting things as I found them, replacing the dsPIC several times along the way.  I'm holding off 'till the new board is here & I have a chance to test it.
 
FWIW, I pored over the Microchip dsPIC33E USB Dev Board to see how it was configured.  That prompted a few changes in how I am configuring the new PCB.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
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Antipodean
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:25:55 (permalink)
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mpgmike
 but I need to order a new board (4-layer = $300 US!). 



Have a look at https://jlcpcb.com/
 
A colleague has used them with good results.
 

Do not use my alias in your message body when replying, your message will disappear ...

Alan
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NorthGuy
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:44:04 (permalink)
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mpgmike
I found damage.  I don't know if it happened between #1 & #2 or #6 & #7, but I need to order a new board (4-layer = $300 US!).



May be it was there from the beginning and caused all these problems.
 
Since you're designing a new board, I would add a footprint for a capacitor between PGC and ground not too far from the PIC, just in case.
 
WellPCB has good prices for high quality 4+ layer boards.
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du00000001
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Re: How not to kill a dsPIC33EP? 2019/11/21 10:51:10 (permalink)
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@ mpgmike
If this board is your own design, I'd consider applying (2-layer) PIMs (just as on the Explorer 16/32). You could even copy the pinout of these PIMs. This would allow for easier exchanging microcontrollers - even for using microcontrollers with differing pin counts. And the PIMs are ok with 2 layers.
 
BTW: 4 layers? Until now I always got away with 2 layers unless space was extremely critical. But for prototyping I prefer a somewhat larger board with options for probing etc.
post edited by du00000001 - 2020/05/22 04:12:11

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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mpgmike
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Re: How not to kill a dsPIC33EP? 2019/11/21 17:16:41 (permalink)
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I already ordered a new board.  I'm using 4 layers for 2 reasons; there's too much going on, I need the power & ground planes because it'd be a real pain to route on a 2-layer board.  Secondly, there's a boost converter and several PWM circuits that create lots of noise.  The extra planes help with EMI suppression.  Thanks for the info, though.  Should be here mid-next week (I surely hope!).  Using the time to replace head gaskets in a friend's Caddy, with new steel threads in the aluminum block, head studs, and MLS gaskets.  I'll reinforce the mains while I have it apart.  Same problem, aluminum threads in the block.

I don't need the world to know my name, but I want to live a life so all my great-grandchildren proudly remember me.
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_dex
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Re: How not to kill a dsPIC33EP? 2020/05/22 03:38:20 (permalink)
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I killed my two EP dSPICs when I swap programming cable from 30F board(5V) to EP board (3.3) before rebuilding the EP Project. Before that step it seems it still have 5V on Vpp line.
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du00000001
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Re: How not to kill a dsPIC33EP? 2020/05/22 04:17:11 (permalink)
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_dex
I killed my two EP dSPICs when I swap programming cable from 30F board(5V) to EP board (3.3) before rebuilding the EP Project. Before that step it seems it still have 5V on Vpp line.



Whether on Vpp or on Vcc - what do you expect? Your car won't (most likely) stop either automatically in front of a wall.
Rule: Making an error once may happen. Repeating that error might be a sign of ignorance.
To say the least.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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_dex
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Re: How not to kill a dsPIC33EP? 2020/05/22 04:54:34 (permalink)
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I would expect that if the debugger is not active there is no Voltage on Vpp.
My car has a radar so yes it will stop in front of the wall.
No ones is perfect, two killed is not bad result.
post edited by _dex - 2020/05/22 05:00:34
#32
du00000001
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Re: How not to kill a dsPIC33EP? 2020/05/22 05:14:52 (permalink)
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_dex
I would expect that if the debugger is not active there is no Voltage on Vpp.
My car has a radar so yes it will stop in front of the wall.
No ones is perfect, two killed is not bad result.



I would expect the debugger to hold the last settings unless told otherwise  wink
 
Although my car has a radar as well, it won't stop in front of a wall.
The manual clearly says: "won't stop for non-moving obstacles".
(Plus giving some nice depictions of situations that are likely occur and could result in severe crashes.)
Better check your manual before relying on radar and software to save you life !

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
#33
_dex
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Re: How not to kill a dsPIC33EP? 2020/05/22 06:13:21 (permalink)
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The car has actually two radars, for a hot redundancy. The first one is my Left eye and the second is the right one.
So end of the joke. Back to debugger if it can change Supply voltage, why not to set it to 0, or to Tristate when you are not programming, debugging or running. Default state = tristate. Never mind I survived.
 
The moral of my story is that debugger keeps last used Vcc on its pins, until new is rebuild. So this is dangerous when we work with two boards 3 and 5V simultaneously. I finished 5V debugging session swapped to the 3V board and then bang, dead. Probably(not sure) I even set 3V Project as main before rj45 swap, I do not remember.
post edited by _dex - 2020/05/22 06:27:26
#34
du00000001
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Re: How not to kill a dsPIC33EP? 2020/05/22 08:12:30 (permalink)
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Why not switch off the supply?
Because in the same case in which you're supplying the board during programming and debugging, you may want to "just run" the board without changing the supply. (This is a use case I'm applying often: "program and evaluate the performance".)
While it cost you 2 controllers, there's nothing wrong with this behavior. It's just about not forgetting to change the settings prior attaching a new target. OR: (logically) disconnecting the debugger. In which case I'm quite sure the power output will be stopped. Ever seen this item in the menu?
post edited by du00000001 - 2020/05/25 03:38:47

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
#35
_dex
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Re: How not to kill a dsPIC33EP? 2020/05/25 03:12:56 (permalink)
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I am guilty as said before. Program and Evaluate I have to say I do not have it.
#36
RISC
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Re: How not to kill a dsPIC33EP? 2020/05/25 03:22:49 (permalink)
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Hi,
I generally use 2 versions of MPLAB X.
This allows some flexibility for various projects :
* dedicate one debugger per project and avoid that it keeps upgrading / downgrading firmware. 
* have some specific settings for tools which are not saved in the project 
* debug projects which use 2 PIC with a lot of flexibility
...
Regards
 
#37
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